A positioning technology is a technology in which location information of a mobile terminal is obtained by using wireless communications network resources, to determine a geographical location of the mobile terminal.
In the prior art, two common positioning technologies are an uplink time difference of arrival (UTDOA) positioning method and an observed time difference of arrival (OTDOA) positioning method. In the UTDOA positioning method, a time of arrival (ToA) of a positioning signal sent by a mobile terminal is measured at each base station, a time difference of arrival, at the base stations, of the positioning signal, that is, a reference signal time difference (RSTD) is obtained according to the ToA, the RSTD is reported to a positioning server, and finally, the positioning server determines a location of the mobile terminal according to the RSTD. The OTDOA positioning method is similar to the UTDOA positioning method. A difference lies only in that, in the OTDOA positioning method, each base station sends a positioning signal, and a mobile terminal measures ToAs of the positioning signals and reports an RSTD.
In actual application, because a timing alignment error (TAE) exists between base stations in a system, local clocks of the base stations are generally not in complete synchronization. In this case, a measured RSTD not only includes a time difference of arrival, at different base stations, of a positioning signal, but also introduces a deviation between the local clocks of the base stations. This inevitably causes an error in final positioning calculation and causes a deviation in a positioning result.
In conclusion, in an existing positioning method, because the TAE is introduced during RSTD calculation, a deviation exists between a finally obtained positioning result and an actual location of a mobile terminal.